Above knee amputation, often referred to as an “AKA” (and an above knee prosthesis as an “AK), is the 2nd most common form of amputation. The technical name for this level of amputation is “transfemoral”, literally meaning across-the-femur. Prosthetic advances for amputees of this level continue to increase at a rapid pace, in both socket design and knee and foot componentry. Microprocessor knee systems, once considered experimental, are becoming the standard of care. There are now even externally powered knee systems as well. The continued advancement in Microprocessor knee systems are allowing amputee's greater freedom and mobility than ever before. The C-LEG, Rheo, Orion and Plie knees are a few examples of this technology. Now the ability to walk safely down stairs step over step and negotiate ramps (one of the most difficult walking tasks an amputee faces) has become a reality because of this type of knee. Socket design is ever changing as well. One of the newest technologies in this is called the High-Fidelity Interface. Paul Burnette, CPO, recently became one of the only two prosthetists in the California Bay Area licensed in the HiFi Interface.
“We wanted to license our revolutionary socket design to a select group of prosthetic companies throughout the country that shared our same clinical expertise, commitment to patient satisfaction and desire for innovation. Our plan is to continue to add prosthetic facilities into our professional HiFi network and to continue to create clinical solutions and products to improve patient performance,” said Randall Alley, Biodesigns CEO and chief prosthetist.
The patent-pending HiFi Interface was developed by Alley, who trained Paul in the fitting technique using a specialized casting system. The HiFi Imaging Device compresses the limb in specific areas during the casting process to ensure that the optimum compression and tissue release is transferred to the new socket. According to Alley, patients upon feeling the compression and release imparted by the casting device are immediately able to feel the advantage of the HiFi Interface design.
The HiFi Interface offers a radical departure from traditional socket designs, in which a patient’s soft tissue in the residual limb is simply encapsulated, with little thought to the biomechanics involved in controlling the motion of the limb within the socket. This restricts the amount of control a socket can impart upon the bone buried beneath the soft tissue. Because the bone is centered in the tissue and in a traditional socket this tissue does not offer much resistance to bone motion, the patient expends a significant amount of energy inside the socket merely moving the bone rather than using it to transmit force or torque to the prosthesis.
In contrast, the HiFi Interface’s design consists of four struts, which compress and preload tissue; an alternating pattern of open areas allows a significant volume of the limb’s tissue to exit or flow out of the way. Now the socket is able to connect closer to the bone, minimizing or eliminating the movement of the bone within the socket so the patient has more control, function, and comfort.
Benefits to the limb-loss patient
More energy efficient. It preserves motion rather than absorbing it so that more of the wearer’s input is converted to prosthetic output.
High level of stability.
Increased comfort; more effective heat dissipation.
Enhanced range of motion.
More intimate fit for increased functionality.
The perceived weight of the prosthesis is significantly less.